Abstract

Structural changes in subcortical nuclei
may underlie clinical symptoms of mood disorders. The
goal was to determine whether macrostructural changes
exist in brain areas assumed to be involved in regulation
of mood and whether such changes differ between major
depressive disorder and bipolar disorder. A case–control
design was used to compare volumes of all major
subcortical nuclei. Brains of patients with major
depressive disorder (n = 9) or bipolar disorder (n = 11)
or of individuals without a neuropsychiatric disorder
(n = 22) were included. Exclusion criteria were a history
of substance abuse or histological signs of neurodegenerative
disorders.Volumes of the striato–pallidal nuclei,
of the hypothalamus, thalamus, amygdala, hippocampus
and basal limbic forebrain were determined in the right
and left hemisphere by planimetry of 20 μm whole brain
serial paraffin sections. Comparisons between patients
with bipolar disorder, major depressive disorder and
controls showed a significant (Λ = 0.35, F20,56 = 1.93,
P = 0.028) overall difference in volumes of all investigated
regions with strong effect sizes ( ƒ > 0.40) contributed
by the hypothalamus, external pallidum, putamen
and thalamus. As compared to controls, a strong
effect size (ƒ > 0.40) was found in the bipolar group for
smaller volumes of the hypothalamus, external pallidum,
putamen and thalamus,whereas in patients with
major depressive disorder a strong effect size was only
found for a smaller volume of the external pallidum. In
conclusion our data suggest that pathways presumably
involved in mood regulation have structural pathology
in affective disorders with more pronounced abnormalities
in bipolar disorder.